1. Field of the Invention
The present invention relates to a process and apparatus for producing a dihydric phenolic compound. More particularly, the present invention relates to a process and apparatus for producing a dihydric phenolic compound at a high stability and safety, at a high selectivity and with a high efficiency.
Still more particularly, the present invention relates to a process and apparatus for producing a dihydric phenolic compound, for example, catechol or hydroquinone, from a monohydric phenolic compound at an excellent selectivity at a high stability, while containing the reaction liquid temperature of the monohydric phenolic compound in an appropriate range, which process and apparatus are suitable for industrial practice.
2. Description of the Related Art
Processes for producing a dihydric phenolic compound, for example, catechol together with hydroquinone by an oxidation reaction of monohydric phenolic compounds with peroxide compounds, for example, hydrogen peroxide and ketone peroxide, in the presence of specific catalysts are well known from, for example, Japanese Examined Patent Publications No. 52-38,546 (corresponding to U.S. Pat. No. 4,078,006), No. 52-38,547 (corresponding to U.S. Pat. No. 4,072,722), No. 52-38,548 and No. 52-38,549.
In the conventional processes for producing dihydric phenolic compounds, however, an industrial means for industrially and easily controlling the rapid temperature rise in the reaction liquid for the oxidation reaction of the monohydric phenolic compound due to the heat generated by reaction has not been concretely known. Therefore, the conventional processes are disadvantageous in that not only an explosion of ketoneperoxide contained in the reaction liquid cannot be surely prevented, but also the selectivity of the target dihydric phenolic compound significantly decreases due to the rapid rise of the reaction liquid temperature, and the yield of the dihydric phenolic compound decreases. Accordingly, when a high safety of the reaction procedure and a high selectivity of the target dihydric phenolic compound are required above all, the reaction procedure must be carried out at a low conversion of the monohydric phenolic compound.